Snow blights bring about a significant disease damage onto gramineous plants, wheat, barley, oat and leguminous plants in cold snowy districts and are identified in accordance with each corresponding pathogenic fungus by the denotations, such as Typhula snow blight (Typhula incarnate), Typhula snow blight (Typhula ishikariensis), Fusarium snow blight (Fusarium nivale f. sp. graminicola), Pythium snow blight and Sclerotinia. These diseases are characterized by causing damages on gramineous plants, wheat, barley, oat and leguminous plants under the laid snow, whereby the damaged plant may, after the thawing of snow, be dead by rotting of the foliage and be blighted upon drying or may suffer from retarded growth. Such a damage due to snow blight diseases is well known, especially, for lawn grass. Since the damage by snow blight is caused on plants, especially gramineous plants, beneath the laid snow, a prophylaxis or therapy of snow blight diseases is difficult to realize. There have hitherto been used for controlling snow blights agents based on organic copper compounds, such as those containing, for example, copper 8-hydroxyquinolate, as the effective component; mepronyls containing 3'-isopropoxy-2-methylbenzanilide as the effective component; and agents based on hydroxyisoxazole, such as those containing potassium 3-hydroxy-5-methyl-isoxazole as the effective component.
These conventional controlling agents are usually applied to the ground twice or thrice before continuous snow coverage has been settled over the ground. Here, a problem of environmental pollution may be provoked by an accidental flooding off or elution of the controlling agent by, for example, rain fall, into watering canals. In addition, so-called acquisition of resistance against the controlling agent may occur also in the pathogenic fungi of snow blights, bringing about a problem in the effectiveness of these controlling agents. Under these circumstances, attempts have been made for utilizig antaginistic reactions (competition, antibiosis and parasitism) between microbes which may be harmonic to ecosystem, by sorting out pertinent microbes. For such microbes, there have been disclosed those in the genus of Acremonium (Canadian Journal of Botany, 57(20), 2122-2139), Trichoderma haldianum (Japanese Patent Application Kokai Hei-6-192028), Typhula acoryzae (Japanese Patent Application Kokai Hei-5-286819); and those in the genus of Pseudomonas (Japanese Patent Application Kokais Hei-6-211616, Hei-7-25716 and Hei-7-289242). However, it is difficult to sort out an antagonistic microbe active to all the above-mentioned five pathogenic fungi of snow blights and, thus, only a report has hitherto been given for a strain in the genus of Trichoderma (U.S. Pat. No. 5,418,615) for such a microbe. On the other hand, microbes in the genus Humicola are known to grow in mild and high temperature regions above 25.degree. C.